System and method for link and media access control layer transaction initiation procedures

ABSTRACT

A system and method of implementing a radio link protocol and dynamic partial echo management for a transaction oriented packet data communication system. A data backlog is described with a media access control layer controller and transmitting a BEGIN protocol data unit transmitted to a receiver. A media access control layer transaction is initiated in response to the transmitting of the BEGIN frame.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional ApplicationSerial No. 60/085,752 filed May 17, 1998, and entitled System and MethodMedium Access Control in a Wireless Data Communication System.

BACKGROUND OF THE INVENTION

This invention relates to link and media access layer transactioninitiation procedures in a communication system, and more particularly,to such procedures in time slotted communication systems.

Link layer recovery protocols are used for error and loss recovery indata communication systems. Link layer recovery is especially crucialfor wireless communications due to the particularly harsh loss and errorcharacteristics of the link.

Typically, a link layer recovery protocol is initialized at the time ofconnection establishment. Also, in the case of data link protocols forcellular communications, the radio link protocol (RLP) is notimplemented at the base station but typically situated back in thenetwork so that data flows across the connection seamlessly as themobile traverses multiple cells (across multiple handoffs). When aconnection is established, the network typically assigns a uniquetemporary identifier which may be associated with a data link connectionto a specific mobile station. For example in Cellular Digital PacketService (CDPD), the Mobile Data link Protocol (MDLP) is established atpacket data registration, and a Temporary Equipment Identifier (TEI) isassigned to the mobile station. The TEI is used by peer data link layerentities for subsequent data transfer.

Packet data transactions tend to be bursty with possibly long periods ofinactivity between transactions. For mobile stations involved inintermittent transactions, with long inter-transaction times (eventhough each transaction may involve significant data transfer),maintaining RLP back in the network has the following disadvantages:maintaining the RLP state information across long idle periods is a veryinefficient use of network resources; moving the RLP back into thenetwork has an adverse impact on performance due to increased round tripdelay; moving the RLP back into the network makes it harder to useadaptive modulation and incremental redundancy schemes, that can have asignificant throughput advantage; maintaining a unique identifier acrosslong idle periods is very inefficient and requires the use of a largeidentifier field (for example the TEI in CDPD); and using theidentifiers in each Medium Access control (MAC) layer transmission isdesirable to avoid ambiguity, but long identifiers are wasteful of RFbandwidth.

In a TDMA Digital Control Channel (DCCH), a 7 bit Partial Echo (PE)field has been used as a mobile station identifier. However, for userswith intermittent packet transactions, there is significant probabilityof ambiguity with 7 bit PEs.

The present invention is directed to overcoming, or at least reducing,the effects of one or more of the problems set forth above.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a system andmethod of implementing a radio link protocol and dynamic partial echomanagement for a transaction oriented packet data communication system.The method performs the steps of determining a data backlog with a mediaaccess control layer controller and transmitting a PDU to a receiver.The method further performs the step of initiating a media accesscontrol layer transaction in response to the transmitting of the BEGINPDU.

Also in accordance with the present invention, a system for implementinga radio link protocol (RLP) and dynamic partial echo management for atransaction oriented packet data system. The system comprises a mediaaccess control layer controller for determining a data backlog in amedia access control layer buffer and a media access control layertransmitter for transmitting a BEGIN Protocol Data Unit to a receiver.The system also includes a means for initiating a media access controllayer transaction in response to the transmitting of the BEGIN ProtocolData Unit.

These and other features and advantages of the present invention willbecome apparent from the following detailed description, theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a communication system illustrating theoperation on a packet data channel in accordance with the invention;

FIG. 2 is a graph showing the probability of two or more active usershaving the same partial echo;

FIG. 3 is a block diagram illustrating an examplary implementation of aMedia Access Control (MAC) layer from the Layer 2 block in FIG. 1;

FIG. 4 is a block diagram describing the internal structure of a mobilestation MAC transmission controller block shown in FIG. 3;

FIG. 5 is a state diagram describing a router process for the mobilestation transmission controller described in FIG. 4;

FIG. 6 is a state diagram describing a transmit controller process ofthe mobile station transmission controller described in FIG. 4;

FIG. 7 is a state diagram describing another part of the transmitcontroller process of the mobile station transmission controllerdescribed in FIG. 4;

FIG. 8 is a state diagram describing another part of the transmitcontroller process of the mobile station transmission controllerdescribed in FIG. 4;

FIG. 9 is a state diagram describing another part of the transmitcontroller process of the mobile station transmission controllerdescribed in FIG. 4;

FIG. 10 is a state diagram describing a retrieve retransmit data blocksprocess performed by the transmit controller (TCTX) block of FIG. 4;

FIG. 11 is a state diagram illustrating a retrieve new data blocksprocess performed by the transmit controller (TCTX) block of FIG. 4;

FIG. 12 describes a construct Protocol Data Unit (PDU) process, atransmit (TxT) table, and a sub-channel controllers transmit (SCCxT)table used by the TCTX block of FIG. 4;

FIG. 13 illustrates a physical control field (PCF) process that isexecuted by the mobile station transmission controller described in FIG.4;

FIG. 14 illustrates an automatic retransmission request (ARQ) statusprocess that is executed by the mobile station transmission controllerdescribed in FIG. 4;

FIG. 15 is a state diagram illustrating a mobile station receivecontroller process preformed by the receiver controller block of FIG. 4in the context of transaction initiation;

FIG. 16 is a state diagram illustrating a mobile station receivecontroller process preformed by the receiver controller block of FIG. 4while a fixed coding mode ARQ transaction is in progress;

FIG. 17 is a state diagram illustrating an update receive (Rx) stateexecuted by the receive controller block of FIG. 4 when a data block isreceived;

FIG. 18 is a state diagram illustrating a mobile station receive table,an initialize receive controller (TCRX) parameters process, and a BEGINPDU process which are executed by the receive controller of FIG. 4;

FIG. 19 is a state diagram illustrating a mobile station channel accessmanager (CAM) block of FIG. 3;

FIG. 20 is a state diagram illustrating the choose transmit controller(TCy) process and send coded MAC_PDU process which are executed by theCAM block of FIG. 3;

FIG. 21 is a state diagram illustrating a mobile station sub-channelcontroller process (SCC) block of FIG. 3;

FIG. 22 is a state diagram illustrating a check destination and extractcoded MAC_PDU process that is executed by the SCC block of FIG. 3 onobtaining data from the physical layer of FIG. 3;

FIG. 23 shows a signal flow diagram for downlink BEGIN PDU handshakeprocess between a base station (cell) and a mobile using a stop and waitprocedure;

FIG. 24 is a signal flow diagram of the downlink BEGIN PDU handshakeprocess between the cell and the mobile without using a stop and waitprocedure;

FIG. 25 is a signal flow diagram for an uplink BEGIN PDU handshakeprocess between a cell and mobile;

FIG. 26 is a signal flow diagram for an uplink BEGIN PDU handshakeprocess between the cell and the mobile;

FIG. 27 is a signal flow diagram for a process of assigning an activemobile identity (AMI) on a downlink different from AMI suggested on theuplink; and

FIG. 28 is a flow diagram illustrating an AMI assigned on downlink thatis the same as AMI suggested on the uplink.

DETAILED DESCRIPTION

In describing the invention this application uses the media accesscontrol (MAC) layer assumptions which are based on the Open SystemInterconnections (OSI) model. OSI is an internationally accepted framework of standards for communication between different systems made bydifferent vendors. Most of the dominant communication protocols usedtoday have a structure based on the OSI model. The OSI model organizesthe communication process into seven different categories and placesthese categories in layered sequence based on their relation to theuser. Layer 7 through 4 deal with the end to end communication messagesource and the message destination. While Layers 3 through 1 deal withnetwork access.

Layer 1, the physical layer, deals with the physical means of sendingdata over lines i.e. the electrical, mechanical and functional controlof data circuits. Layer 2, the data link layer, deals with proceduresand protocols for operating communication lines. Layer 3, the networklayer, determines how data is transferred between computers and routingwithin and between individual networks.

It is appreciated that the packet data channel is capable of supportingmultiple modulations. The MAC layer is provided with frames of Layer 3and translates them into a byte stream using flag delimiters. A radiolink protocol (RLP), also referred to as a retransmission link protocol,is used to transfer frames of Layer 2 between a cell and the mobilestation and vice versa. The byte stream of Layer 3 is segmented into RLPframes, and a sliding window retransmission scheme is used forin-sequence delivery and recovery.

MAC layer transaction preferably starts with the transmission of a BEGINframe. On the uplink and downlink, the MAC layer converts the frames ofLayer 3 into a byte stream and packs the byte stream into a series ofCONTINUE frames. The last new data burst of a transaction is transmittedusing an END frame.

The BEGIN frame of each transaction is transmitted using 4-levelmodulation in a stop and wait mode to obtain an acknowledgment from thereceiver. On reception of the BEGIN frame, the receiver initializes anRLP. The BEGIN frame is also used to initialize a partial echo (PE) forthe transaction, and to specify the mode of operation for subsequentautomatic retransmission request (ARQ) mode CONTINUE frames in thattransaction.

There are two possible modes of operation for ARQ mode CONTINUE frameson the downlink and uplink. The first is incremental redundancy (mode 0)and the second is fixed coding (mode 1). It is appreciated that bothmode 0 and mode 1 operate with either fixed modulation or adaptivemodulation.

ARQ checks for errors in transmitted data. The sender encodes anerror-detection (check) field in the transmitted data based on thecontents of the message. The receiver then recalculates the check fieldand compares it with the check field received. If the check fieldsmatch, an ACK (acknowledgment) is transmitted to the sender. If bothcheck fields do not match, a NAK (negative acknowledgment) is returned,and the sender retransmits the message.

For both uplink and downlink transmissions, bitmap feedback in the formof an ARQ status is provided. In addition, ACK/NAK feedback is providedon a per time slot basis for uplink transmissions.

FIG. 1 shows a high level block diagram of operation on the packet datachannel 100 in accordance with the invention. A transaction orientedpacket data communication system 105 is shown where Layer 3 frames 110are provided to the Layer 2, MAC Layer 115, at the transmitter 120 andare translated into a byte stream using flags for demarcation. Thispermits the MAC layer 115 to provide a unified transport mechanism fordifferent Layer 3 protocols. This byte stream is segmented into RLPframes and assigned a frame sequence number (FSN). The FSN is notexplicitly transmitted as part of the RLP frame.

For higher throughput in either mode, Layer 1 125 data is mapped intosymbols chosen from a 4-level, 8-level or 16-level modulation based onknowledge of Layer 2 backlog and channel quality feedback 130 from thereceiver 135. The channel quality is measured in terms of the signal tointerference plus noise ratio, $\frac{C}{1 + N}$

at the input to the decoder in the Layer 2 block 140 via physical layer145 at the receiver 135. The decoder 140 then outputs the Layer 3 frames150.

The IS-136 Digital Control Channel uses a temporary mobile stationidentifier also called a Partial Echo (PE). The PE is assumed to be anabbreviated Mobile Station Identity (MSID), i.e., the last 7 bits of theMSID is treated as the PE. Due to this mechanism, there is a significantprobability that two or more active users would use the same PE, andthat erroneous protocol states would result frequently due to inabilityof mobiles to resolve their PE's correctly.

In FIG. 2, this probability is shown as a function of the number usersthat are simultaneously active on the channel. In packet dataapplications (as opposed to voice or circuit data applications), it isquite possible to have ten or more active users at any given timesharing the same channel. In these cases, the probability of partialecho duplication reaches 25% and higher which is unacceptable for propersystem operation.

The problem is selectively solved by assigning a proposed PE value (suchas a dynamic PE) or an active mobile identity (AMI), to every mobile forall downlink transactions, and for uplink transactions which requiremore than a single burst. Both the downlink and uplink transactions arepart of a MAC layer transaction. The AMI serves as a unique (assigned)local identifier to be used by the transmitter and the receiver for theduration of the transaction on a particular packet data channel. A newAMI is assigned for each new transaction thus eliminating the potentialfor ambiguity. The same AMI may be used in either direction (i.e., theAMI assignment is initiated by the uplink or downlink transaction,whichever begins first, and remains assigned till the end of datatransfer in both directions).

A new transaction is initiated when a transmission opportunity isidentified and if the transmit buffer contains new data. Downlinktransactions may be ACK or NAK but uplink transactions are always ACK.Preferably every MAC layer transaction starts with a BEGIN Protocol DataUnit (PDU) handshake and proceeds with the transmission of a series ofCONTINUE PDUs. The BEGIN PDU contains the proposed partial echo valueand/or proposed mode of operation. ARQ mode CONTINUE PDUs may betransmitted in Incremental redundancy Mode (mode 0) or Fixed coding Mode(mode 1), and ARQ procedures for the two modes are different.Supervisory ARQ Status PDUs are used to provide the transmitter withperiodic feedback of the receiver state.

The BEGIN PDU handshake (i.e., ACK transfer of the BEGIN PDU)establishes the AMI and the mode of operation for subsequent CONTINUEPDUs. It is appreciated that on multi-rate channels, it may alsoselectively be used to carry out phase assignment.

Base stations (also know as cells) selectively initiate downlinktransactions through the transmission of a BEGIN PDU. The parametersindicated by the BEGIN PDU include: a Mobile Station Identity (MSID); anARQ Mode (AM) indicating whether the transaction is ACK or NAK; a PollIndicator (PI) for ACK transactions indicating whether the mobilestation is required to provide an ACK via an ARQ Status PDU; an AMIvalue to be assigned to the mobile station; a Mode Indicator (MI)indicating whether the mode of operation for subsequent downlinkCONTINUE PDUs is Fixed Coding or Incremental Redundancy and a PhaseAssignment (PA) indicating the phase for the transfer of subsequent dataon the uplink or downlink.

If an AMI has already been assigned to the mobile station, the basestation assigns the same AMI value within the BEGIN PDU. If the mobilestation does not have a valid AMI, the base station randomly chooses anAMI value from the set of allowable values and assigns it to the mobilestation using the BEGIN PDU. The base station Transmit Controllerinitializes a RLP in the indicated mode (IR or FC) on transmission ofthe BEGIN PDU. The mobile station receive controller initializes a peerRLP in the assigned mode on receipt of the BEGIN PDU.

FIG. 3 illustrates an example implementation of the Media Access Control(MAC) 155 Layer in a duplex wireless data communication system. The MAC155 interfaces with Layer 3 160 (network layer), physical layer (Layer1) 165 (which includes a MAC layer transmitter 166 and MAC layerreceiver 167) and with the management entity 170. In this example, theMAC 155 provides data and expedited control delivery services to Layer 3160 and other higher layer entities. The MAC 155 uses Layer 1 165, viathe MAC layer transmitter 166, for delivery of its PDUs over a radiointerface 175. The management entity 170 initializes, terminates,suspends, resumes and configures MAC 155 operation. The managemententity 170 also monitors the MAC 155 for errors. The management entity170 also provides dynamic PE management for the transaction orientedpacket data communication system 105, FIG. 1. The MAC 155 includes twoService Access Points (SAPs): SAP1 for regular data and SAP0 forexpedited data and control. Each SAP has a corresponding transmit buffer(TXB), segmenter (SGM), desegmenter (DSGM), frame extractor (FRX) andtransmission controller (TC). A channel access manager (CAM) 180multiplexes the PDUs from the different transmission controllers (alsoknown as ARQ engine) TC0 and TC1, FIG. 3, and provides priorityscheduling. The CAM 180 is also responsible for uplink random access. AMAC subchannel controllers (SCC) 185, preferably up to 9 (SCC0 throughSCC8), control transmission over each of the wireless data subchannels.The MAC Layer Controller (MLC) 190 controls overall MAC configurationand interfaces with management entity 170. PDU encoders (PENC0 andPENC1) and decoders (PDEC0 and PDEC1) provide channel coding/decodingfor the MAC PDUs in mode 0 (incremental redundancy) or mode 1 (fixedcoding). A mode 0 segment encoder (SENC0) and decoder (SDEC0) providecoding/decoding, interleaving/deinterleaving and blocking/deblocking inincremental redundancy mode of transmission.

FIG. 4 shows internal structure of a MAC transmission controller (TC)for a mobile station from FIG. 3 and located within the MAC layer 2 115,FIG. 1, of the transmitter 120. The transmission controller 192 consistsof the following sub-blocks: a transmit controller (TCTX) 195, receivecontroller (TCRX) 200, broadcast controller (TCB) 205 and router (TCRT)210. The transmit controller 195 is connected to the segmenter (SGM0 andSGM1, FIG. 3), PDU encoder (PENC0 and PENC1), CAM 180, MLC 190 and TCRT210, FIG. 4. The TCRX 200 and TCB 205 controllers are connected todesegmenter (DSGM, FIG. 3), MLC 190 and TCRT 210, FIG. 4. The TCRT 210is connected to TCTX 195, TCRX 200, TCB 205, MLC 190, FIG. 3, and PDUdecoder (PDEC0 or PDEC1).

FIG. 5 is a state diagram that describes a router process for the mobilestation transmission controller 192 of FIG. 4. The router 210, FIG. 4,preferably transfers decoded frames to an appropriate process (transmit,receive or broadcast controllers) within the transmission controller192. The router 210 is also preferably employed to receive controlinformation, such as phase assignment, poll indication, broadcast changenotification and page continuation indication that may selectively betransmitted to the mobile by a peer transmission controller located at abase station. The router 210 tracks whether the mobile station is in thesleep state 215, FIG. 5, or awake state 220 and whether the AMI has beenassigned to the mobile. It is appreciated that depending on theconditions, the router 210, FIG. 4, routes received frames accordingly.

The router 210 receives decoded frames from the CAM 180, FIG. 3, via adata.ind( ) primitive. The router 210, FIG. 4, may be moved by the MLC190, FIG. 3, from the sleep 215, FIG. 5, to awake 220 states and backvia wake.req( ) and sleep.req( ) primitives respectively. The router210, FIG. 4, issues data.ind( ) primitives to receive, transmit orbroadcast controllers (TCRX 200, TCTX 195 and TCB 205) of FIG. 4. Therouter 210 informs the MLC 190, FIG. 3, about a page or pagecontinuation reception (via wake.ind( )), broadcast change notificationreception (via bcn.ind( )) and new phase assignment (via phase.ind()/phase.req( )).

FIG. 6 illustrates the idle state interaction of the transmit controller192, FIG. 4, with the CAM 180, FIG. 3, and a PDU encoder (PENC0 orPENC1). FIG. 6 also illustrates an example of a transition to the waitfor assignment state.

In FIG. 6 a retrieve block for transmission in a BEGIN PDU process ispreferably executed in the beginning of the uplink transaction so as toretrieve data from the segmenter (SGM0 or SGM1FIG. 3) and to determinewhether the end of transaction process should be executed based on thetransaction size.

The transmit controller 192, FIG. 4, receives poll.ind( ) primitivesfrom the CAM 180, FIG. 3, when a transmission opportunity on the uplinkoccurs. The transmit controller 192, FIG. 4, responds with the poll.res() primitive indicating whether the process may selectively send data. Inthe idle state, the TCTX 195, FIG. 4, sends BEGIN or ARQ STATUS PDUs. Ifthe CAM 180, FIG. 3, provides a transmission opportunity to this TCTX195, FIG. 4, the TCTX 195 responds with poll.con( ) primitive. The TCTX195 constructs a PDU and passes the PDU to a PDU encoder via data.req( )and, in case of BEGIN PDU, enters the wait for assignment state. Whenretrieving data for BEGIN PDU, the TCTX 192 counts the number of datablocks in a buffer (TXB0 or TXB1, FIG. 3) and determines if it shouldcommit to the end of the transaction (NB_Tx<NB_Max and End_Tx_Flag=True)from the start or if the transaction should start as unbounded(NB_Tx=NB_Max and End_Tx_Flag=False). If the TCTX 195, FIG. 4, commitsto the end of transaction from the start the TS (Transaction Size) fieldin the BEGIN PDU is set to the size of the transaction in data blocks,otherwise it is set to NB_Max (Maximum value of NB_Max is 63).

FIG. 7 shows the wait for assignment state interaction, described inFIG. 6, of the transmit controller 192, FIG. 4, with the CAM 180, FIG.3, and PENC1. FIG. 7 also describes both a count new data blocks processand a retrieve ARQ status bitmap process. The count new data blockprocess is preferably executed every time the TCTX 195, FIG. 4, has todetermine the amount of data in the MAC buffer, FIG. 3, that haspreferably never been sent over the air but still may selectively beincluded in the current transaction. The retrieve ARQ status bitmapprocess involves communicating with the receive controller (TCRX) 200,FIG. 4, to retrieve a bitmap indicating the state of the ARQ protocolfor the downlink transaction.

The transmit controller 192 receives poll.ind( ) primitives from the CAM180, FIG. 3, when a transmission opportunity on the uplink occurs. Thetransmit controller 192, FIG. 4, responds with the poll.res( ) primitiveindicating that the transmit controller 192 may selectively send data.In the wait for assignment state, the TCTX 195 may selectively send ARQSTATUS PDUs (if polled for it by peer transmission controller 192). IfCAM 180, FIG. 3, provides a transmission opportunity to this TCTX 195,FIG. 4, the CAM 180, FIG. 3, sends a poll.con( ) primitive. The TCTX195, FIG. 4, retrieves ARQ status bitmap, constructs a PDU, and passesthe PDU to the PDU encoder via a data.req( ). When counting new datablocks, the TCTX 195, FIG. 4, first checks if it has already committedto the end of current transaction (End_Tx_Flag=True). If this is thecase, the TCTX 195 counts only the blocks remaining until the end ofcurrent transaction (indicated by BST_Status) and ignores data thatmight have arrived to the buffer (TXB0 or TXB1, FIG. 3) aftertransaction end had been committed to. If not, the TCTX 195, FIG. 4,counts all data in MAC buffers, TXB0 or TXB1, FIG. 3, (indicated by thesum of BST_Status and TXB_Status). If the number of new blocks countedin such a way is larger than NB_Max, the transaction may selectivelycontinue as unbounded. Otherwise the end procedure is required.

FIG. 8 illustrates transitions between the idle, wait for assignment andtransaction in progress in mode 0 and mode 1 states. The TCTX 195, FIG.4, may selectively transition from the wait for assignment state to oneof the transaction in progress states (depending on uplink mode(UL_Mode) negotiated with the base station) after receiving positiveacknowledgment to its BEGIN PDU via a PCF (as indicated by data.con( )primitive from the CAM and Error=Null condition being True) or afterreceiving the downlink ARQ status PDU with AMI assignment (as indicatedby data.ind(ARQ_Status_Rx) primitive from TCRT 200 and conditions of WAIand AMI=AMI_Idle being False). In the wait for assignment state timersT_WA and T_BOFF_START may selectively expire and the TCTX 195 mayselectively transition back to the idle states. These timers designatethe amount of time the mobile station should wait for the AMI/Modeassignment via ARQ Status PDU before the mobile station is allowed torepeat its access attempt.

In the transaction in progress (mode 0 and mode 1) states, the TCTX 195may selectively receive acknowledgments via a PCF (data.con( ) from CAM180, FIG. 3) and via ARQ Status PDU (data.ind( ) from TCRT 200, FIG. 4).If the transmit table 230, FIG. 12, is empty and there is no new data(no data backlog) to send (NB_Tx<=0), the transaction is completed andthe TCTX 195, FIG. 4, selectively transitions to the idle state.Otherwise, the TCTX 195 remains in the transaction in progress states,unless the inactivity timer (T_INAC) expires.

FIG. 9 describes the transaction in progress state, seen in FIG. 8,interaction of the transmit controller 192, FIG. 4, with the CAM 180,FIG. 3, and the PDU encoder (PENC0 or PENC1, FIG. 3). FIG. 9 alsodescribes the find retransmit data blocks process. This process isexecuted selectively every time the TCTX 195, FIG. 4, determines ifthere are any data blocks in the transmit table 230, FIG. 12, that havenot been acknowledged by the receiver and are retransmitable (i.e. thereis a data backlog).

The transmit controller 192 receives a poll.ind( ) primitives from theCAM 180, FIG. 3, when a transmission opportunity on the uplink occurs.The transmit controller 192 responds with the poll.res( ) primitiveindicating whether it can or must send data. In the transaction inprogress state the TCTX 195, FIG. 4, may selectively send ARQ STATUS (ifpolled for it by peer transmission controller) or CONTINUE PDUs. If theCAM 180, FIG. 3, decides to provide a transmission opportunity to thisTCTX 195, FIG. 4, the CAM 180, FIG. 3, sends a poll.con( ) primitive.The TCTX 195, FIG. 4, constructs a PDU, and passes it to the PDU encodervia data.req( ).

FIG. 10 describes a retrieve retransmit data blocks process. The processis executed by the TCTX 195, FIG. 4, every time TCTX 195 constructs theCONTINUE PDU which includes data blocks that have been transmittedpreviously but must be retransmitted again because the receiver failedto decode them properly (i.e. another type of data backlog). The numberof such data blocks depends upon the current modulation (as examples 3blocks for 8-level modulation and 2 blocks for 4 level) and on whetherthe previously transmitted End block has to be retransmitted to informthe receiver about the last sequence number it should expect for thetransaction. If the End block has to be retransmitted(End_RTx_Flag=False), the process generates the End block and places itin the SCCxT table 235, FIG. 12. If after retrieving the retransmit datablocks there is still a space remaining in the PDU, the process fillsthis space with either the redundant End block (if the end procedure isin progress, i.e. End_Tx_Flag=True) or with the filler block (if the endprocedure has not yet been started, i.e. End_Tx_Flag=False).

FIG. 11 illustrates a retrieve new data blocks process. This process isexecuted by the TCTX 195, FIG. 4, every time the TCTX 195 constructs theCONTINUE PDU which includes data blocks that have never been transmittedpreviously (another type of data backlog). The number of such datablocks depends upon the current modulation (as examples 3 blocks for8-level modulation, 2 blocks for 4 level) and on whether the End blockhas to be transmitted to inform the receiver about the last sequencenumber it should expect for the transaction. If the previouslytransmitted End block has to be retransmitted again (End_RTx_Flag=False)or if the number of new data blocks in MAC buffers (TXB0 and TXB1, FIG.3) is smaller than a predefined threshold (NB_Tx<NB_Max), the processgenerates the End block and places it in the SCCxT table 235, FIG. 12.If after retrieving new data blocks there is still a space remaining inthe PDU, the process fills this space up with either the redundant Endblock (if the end procedure is in progress, i.e. End_Tx_Flag=True) orwith the filler block (if the end procedure has not yet been started,i.e. End_Tx_Flag=False).

FIG. 12 describes a construct PDU process 225, a transmit (TxT) table230, and a sub-channel controllers transmit (SCCxT) table 235 used bythe TCTX 195, FIG. 4. The construct PDU process 225 illustrates howvarious control and data fields in the PDUs are filled up with valuesand data. The TxT table 230, FIG. 12, is used to track ARQ state of thetransmit controller 192, FIG. 4, i.e. the status and order of thepreviously transmitted data blocks within the transmit window. The SCCxTtable 235 is used to track the association between blocks and the PDUsand the sub-channels that the PDUs have been transmitted on. The SCCxTtable 235 stores information on all MAC blocks in transit that have notyet been acknowledged via a physical control field (PCF). The SCCxTtable 235 is also used to facilitate construction of PDUs. Both the TxT230 and SCCxT 235 tables are means to determine a data backlog with theMAC layer.

FIG. 13 shows a PCF process that is executed as part of the mobilestation transmit controller 192, FIG. 4. The PCF provides acknowledgmentfor all blocks transmitted in the previous uplink burst on thesub-channel. If the PCF indicates that the previous uplink transmissionon the sub-channel was received, a transmit table corresponding to theblocks transmitted is updated. The ARQ state variables at the TC 192 arealso updated to reflect the PCF acknowledgment. The TC 192 provides adata.con signal to the segmenter (SGM0 or SGM1, FIG. 3) for each blockacknowledged. If the data blocks transmitted in the previous uplinkburst on the sub-channel are negatively acknowledged via the PCF, thenthe data blocks are marked as retransmittable.

FIG. 14 illustrates an ARQ status process that is executed by the mobilestation transmit controller 192, FIG. 4. An ARQ Status PDU may be usedto assign an AMI and mode to the mobile station if the AMI and/or modeproposed by the mobile station are unacceptable. Alternatively, it mayindicate that the mobile station must wait for a subsequent AMI and/ormode assignment. This process also causes an update of the ARQ statevariables and transmit table (TxT 230, FIG. 12) at the TC 192. If a NNDfield in the ARQ Status PDU is set, then the mobile station assumes thatno new Layer 3 data may be transmitted. If an End block was transmittedwhile nearing the end of the transaction, then the End block isacknowledged through an EBR bit in the ARQ Status PDU. If the ARQ statusPDU includes a primary bitmap indicating the receipt status of allblocks within the receive window, then this bitmap is used to update thereceipt and retransmittability status of blocks within the transmittable (i.e., the transmit controller understands the receive window).For each block acknowledged by the bitmap, the TC 192 provides adata.con signal to the segmenter.

FIG. 15 shows the mobile station receive controller process in thecontext of transaction initiation. FIG. 15 illustrates signals obtainedby the receive controller (TCRX) 200, FIG. 4, from the PDU decoder,PDEC0 or PDEC1, FIG. 3 (in state Data.ind). Also shown are signals sentby the TCRX 200, FIG. 4, process to a desegmenter, DSGM0 or DSGM1, FIG.3 (in state Data.ind) and MLC 190 in state StartRx.ind.

BEGIN PDUs are selectively received while the TCRX 200, FIG. 4, is inthe idle state. On receiving a BEGIN PDU from the PDU decoder, PDEC0 orPDEC1, FIG. 3, the TCRX 200, FIG. 4 determines whether the transactionis acknowledged and whether the transaction is bounded (i.e., limited tothe transfer of NB_Rx Data blocks). For ARQ transactions, the TCRX 200also determines the ARQ mode (mode 0 or mode 1) for the transaction andinitializes an ARQ engine (also known as a TC 192, FIG. 4) in theindicated mode. The TCRX 200, FIG. 3, provides for the initiating of aMAC transaction in response to a BEGIN frame.

FIG. 16 illustrates the mobile station receive controller process whilea fixed coding mode ARQ transaction is in progress. FIG. 16 showssignals received by the TCRX 200, FIG. 4, from the TCTX 195 (in statePoll.ind), MLC 190, FIG. 3, (in state StopRx.Req) and the PDU Decoder,PDEC0 or PDEC1, FIG. 3 (in state Data.ind). Also shown are signals inFIG. 16 sent by the TCRX 200, FIG. 4, to the TCTX 195 (the stateData.req), desegmenter, DSGM0 or DSGM1, FIG. 3 (in state error.ind) andMLC 190, FIG. 3 (in state Error.ind).

On being polled by a TC 192, FIG. 4, for ARQ Status, the TCRX 200generates an ARQ status PDU (which contains a bitmap indicating thereceipt status of all blocks in a receive window) and provides it to theTC 192. The CONTINUE PDUs are selectively received while a transactionis in progress. On receiving a CONTINUE PDU from the PDU decoder, theTCRX 200 extracts multiple blocks from the PDU. It is appreciated thatthe number of blocks extracted depends on the downlink modulation. Theblocks are selectively of type end, data or filler. End and fillerblocks are identified by escape sequences at the start of the block. Ifan end block is received, the TCRX 200 preferably sets the last validsequence number for the transaction to the sequence number indicated bythe end block. For each data block extracted, the TCRX 200 executes anupdate receive (Rx) state process.

FIG. 17 shows the update Rx state process executed by the TCRX 200, FIG.4, when a data block is received. FIG. 17 shows signals sent by thereceive controller 200 to the desegmenter, DSGM0 or DSGM1, FIG. 3 (instate Data.ind) and MLC 190, FIG. 3 in state StopRx.ind.

The receive controller 200, FIG. 4, selectively invalidates and discardsthe data block if it lies outside the window or corresponds to a blockthat was previously received. If the data block remains valid, the TCRX200 updates the receipt status of the block. The receive controller 200also updates the two state variables, NR_Rx (sequence number up to whichall data blocks have been received in-sequence) and NL_Rx (last sequencenumber that was received). The receive controller 200 then delivers alldata blocks that have been received in-sequence to the desegmenter anddeletes these entries from a receive table. The process stops when thereceive table is empty and NR_Rx is equal to the last valid sequencenumber for the transaction.

FIG. 18 shows the mobile station receive table 240, an initialize TCRX200 parameters process 245 and a BEGIN PDU process 250 which areexecuted by the receive controller (TCRX) 200, FIG. 4. The receive table240 consists of the block sequence number, data block and receipt statusfor each sequence number within the receive window. The initialize TCRX200 parameters process 245 carries out an initialization of the receivetable 240 and other ARQ state variables. The BEGIN PDU process 250illustrates the initialization of the AMI, mode and the size for thetransaction. It is appreciated that these parameters are extracted fromcorresponding fields within the BEGIN PDU.

FIG. 19 shows the mobile station CAM process for the CAM 180, FIG. 3.FIG. 19 shows signals received from any one of the SCCs 185 (data.con,pcf.ind, data.ind) and the MLC 190 (Open.req, Config.req, Close.req).FIG. 19 also shows the signals sent by the CAM 180 to the transmitcontroller 185 (data.con), PDU decoder, PDEC0 or PDEC1, FIG. 3(data.ind), and MLC 190 (Error.ind).

The CAM 180 determines the order of transmission for coded MAC PDUs frommultiple transmit controllers 185 (SCC0 through SCC8). The CAM 180 pollsthe transmission controllers 185 for MAC PDUs when it is made aware of atransmission opportunity by one of the MAC sub-channel controllers 185.Based on the response to the CAM 180 polls, the CAM 180 polls one of thetransmit controllers 185 for the data. The CAM 180 selectively sendscoded MAC PDUs obtained from one of the PDU encoders (PENC1 and PENC0)to the appropriate SCC 185 for transmission over the air interface 175(also known as the radio interface).

The CAM 180 is also responsible for executing a random access protocolat the mobile station. This function manages channel access incontention mode and all subsequent back-off procedures in case of thefailure of initial access. After successful access, the CAM 180 pollsthe transmit controllers 185 and proceeds by sending PDUs in theassigned slots indicated by sub-channel controllers 185.

In the receive direction, the CAM 180 obtains MAC PDUs from thesub-channel controller 185 and passes them on to the PDU decodercorresponding to the indicated mode.

FIG. 20 illustrates a choose transmission controller (TCy) process 255and a send coded MAC_PDU process 260 which are executed by the CAM 180,FIG. 3. FIG. 20 shows signals sent by the CAM 180 to the TCs (TC1 andTC2, FIG. 3, and poll.ind and poll.con, FIG. 20) and SCCs 185, FIG. 3(data.req). FIG. 20 also shows signals received from the TCs (TC1, TC2,FIG. 3 and poll.res, FIG. 20) and the PDU encoder (PENC0 and PENC1, FIG.3 and data.req, FIG. 20).

The CAM 180, FIG. 3, polls each transmit controller in order of prioritywhen it is made aware of a transmission opportunity by any SCC 185. EachTC (TC0 and TC1) responds with an indication that it selectively senddata, can send data or has nothing to send. Based on the response, theCAM 180 chooses the appropriate TC (TC0 and TC1) to poll for data.Subsequently, the CAM 180 obtains a coded MAC PDU from the PDU encoder(PENC0 and PENC1) that the CAM 180 provides to the appropriate SCC 185for transmission over the air interface 175.

FIG. 21 illustrates the mobile station sub-channel controller (SCC)process. The MAC Layer has preferably 9 sub-channel controllers 185(SCC0 through SCC8), FIG. 3, for a triple rate channel, 6 for a doublerate channel and 3 for a full rate channel. Each sub-channel controller185 handles a packet channel feedback (PCF) operation for thesub-channel and passes coded MAC PDUs between the CAM 180 and thephysical Layer 165.

In FIG. 21, signals are received by the SCC 185, FIG. 3, from thephysical Layer 165 (PHY_DATA.IND), CAM 180 (Data.req) and MLC 190(Open.req, Close.req). Additionally the signals sent by the SCC 185 tothe CAM 180 (pcf.ind, Data.con) and the physical layer 165(PHY_DATA.REQ) are shown.

On obtaining data from the physical layer 165, the SCC 185 checks theAMI to determine if the mobile station is the intended recipient. If thedata is not intended for the mobile station, it is discarded; otherwisethe coded MAC PDU is passed on to the CAM 180. The SCC 185 also obtainscontention and reserved access opportunities via the PCF and polls theCAM 180 for data. Any coded MAC PDU subsequently obtained from the CAM180 is then passed on to the physical layer 165. After the PDU istransmitted, the SCC 185 checks the corresponding PCF field on thesub-channel in order to determine if the PDU was received successfully.The SCC 185 assumes a different PCF structure depending on whether datawas transmitted using contention or reservation. The acknowledgmentstatus obtained via PCF is indicated to the CAM 180.

FIG. 22 illustrates a check destination and extract coded MAC_PDUprocess that is executed by the SCC 185, FIG. 3, process on obtainingdata from the physical layer 165. The SCC 185 may selectively send adata.ind signal to the CAM 180 as part of this process. On obtainingdata from the physical layer 165, the SCC 185 checks the AMI todetermine if the mobile station is the intended recipient. If the datais not intended for the mobile station, it is discarded; otherwise thecoded MAC PDU is passed on to the CAM 180.

FIG. 23 shows a signal flow diagram for downlink BEGIN PDU handshakeprocess between a base station (cell) 265 and a mobile 270 using stopand wait. The BEGIN PDU handshake establishes a unique (assigned) localidentifier referred to as the AMI. The BEGIN PDU handshake alsoidentifies the mode of operation for the subsequent operation. There are4 possible modes of operation: fixed coding and fixed modulation; fixedcoding and adaptive modulation; incremental redundancy and fixedmodulation; and incremental redundancy and adaptive modulation.

In step 275, the cell 265 sends MAC layer BEGIN PDU, to the mobile 270,which specifies the mode of operation of subsequent CONTINUE PDUs andassigns an AMI for the transaction. The RLP is initialized at the cell265 on transmission of the BEGIN PDU and the mobile station 270initializes the peer RLP on receipt of the BEGIN PDU. This step wasshown in the state diagrams when the SCC 185, FIG. 3, receives data fromthe physical layer 165 and passes it on to the CAM 180 in FIGS. 21 and22. The CAM 180, FIG. 3, then receives data from the SCC 185 and thedecoded data is provided to the router (TCRT) 210, FIG. 4 (described inthe FIG. 19 state diagram). The TCRT 210, FIG. 4 receives the data fromCAM 180, FIG. 3, extracts a poll bit (PI), sets ARQ_Status_polledflag=PI and passes the BEGIN PDU to the TCRX 200, FIG. 4 (described inthe FIG. 15). The TCRX 200, FIG. 4, receives the BEGIN PDU from the TCRT210 and initializes the AMI and downlink Mode in FIGS. 15 and 18.

In step 280, the mobile 270 provides an ARQ Status PDU (with a nullbitmap) acknowledging (ACK) the BEGIN PDU to the cell 265. This step wasshown when the SCC 185, FIG. 3, detects a transmission opportunity byreading the PCF and indicates it to CAM 180, FIG. 3, in FIG. 21. The CAM180, FIG. 3, polls the TCTXs 195 in FIGS. 19 and 20. The TCTX 195, FIG.4, on the same step, where Begin PDU is received, indicates to the CAM180, FIG. 3, that it selectively send an ARQ Status PDU in FIGS. 6, 7and 9. The CAM 180, FIG. 3, polls TCTX 195, FIG. 4, for ARQ Status PDUin FIG. 19. The TCTX 195, FIG. 4, polls the TCRX 200 for an ARQ Statusbitmap in FIG. 7. The TCRX 200, FIG. 4, generates ARQ status andprovides it to the TCTX 195 in FIG. 7. The TCTX 195, FIG. 4, sends theARQ status PDU to PDU encoder (PENC0 or PENC1, FIG. 3) in FIGS. 6, 7 and9. The PDU encoder (PENC0 or PENC1, FIG. 3) encodes the PDU and sendsthe encoder PDU to the CAM 180. The CAM 180 passes the encoder PDU on toSCC 185 in FIG. 7. The SCC 185, FIG. 3, then provides data to thephysical Layer 165 in FIG. 21.

In step 285, the cell 265 sends, to the mobile 270, subsequent CONTINUEPDUs in the initialized mode. This step was shown when the SCC 185, FIG.3, receives the data from the physical Layer 165 and passes the data onto the CAM 180 in FIGS. 21 and 22. The CAM 180, FIG. 3, receives thedata from the SCC 185 and the decoded data is provided to the TCRT 210(FIG. 4) in FIG. 19. The TCRT 210, FIG. 4, receives the data from theCAM 180 (FIG. 3) in FIG. 5. The TCRX 200, FIG. 4, receives the ContinuePDU and updates the Rx state in FIGS. 16 and 17.

FIG. 24 is a signal flow diagram of the downlink BEGIN PDU handshakebetween the cell 265 and the mobile 270 without using stop and wait. Instep 290, the cell 265 sends MAC layer BEGIN PDU to the mobile 270 whichspecifies the mode of operation of subsequent CONTINUE PDUs, assigns anAMI for the transaction and assigns the mobile 160 to a particularphase. The cell 265 initializes the RLP on transmission of the BEGIN PDUand schedules subsequent PDUs intended for the mobile 270 on theassigned phase. On receipt of the BEGIN PDU, the mobile station 270initializes the peer RLP and starts listening on the assigned phase.This step was shown when the SCC 185, FIG. 3, receives data from thephysical layer 165 and pass it on to the CAM 180 in FIGS. 21 and 22. TheCAM 180, FIG. 3, then receives data from the SCC 185 and the decodeddata is provided to TCRX 200, FIG. 200, in FIG. 19. The TCRX 200, FIG.200 receives the data from CAM 180, FIG. 3, extracts a poll bit (PI),sets ARQ_Status_polled flag=PI and passes the Begin PDU to the TCRX 200,FIG. 4, in FIG. 5. The TCRX 200, FIG. 4, receives the Begin PDU from theTCRT 200 and initializes the AMI and downlink mode in FIGS. 15 and 18.

In step 295, the cell 265 sends subsequent CONTINUE PDUs to the mobile270 and polls the mobile 270 for feedback. This step was shown when theSCC 185, FIG. 3, receives the data from the physical Layer 165 andpasses it on to the CAM 180 in FIGS. 21 and 22. The CAM 180, FIG. 3,receives the data from the SCC 185 and the decoded data is provided tothe TCRT 210 (FIG. 4) in FIG. 19. The TCRT 210, FIG. 4, receives thedata from the CAM 180 (FIG. 3) in FIG. 5. The TCRX 200, FIG. 4, receivesthe CONTINUE PDU and updates the RX state in FIGS. 16 and 17.

In step 300, the mobile 270 provides bitmap feedback through an ARQStatus PDU to the cell 265. The ARQ Status PDU may selectively indicatethat the assigned mode was unacceptable. This step was shown when theSCC 185, FIG. 3, detects transmission opportunity by reading the PCF andindicates it to CAM 180 in FIG. 21. The CAM 180, FIG. 3, polls both theTCTXs (195, FIG. 4) in FIGS. 19 and 20. The TCTX 195, FIG. 4, on thesame step, where BEGIN PDU is received, indicates to the CAM 180, FIG.3, that it selectively send an ARQ Status PDU in FIGS. 6, 7 and 9. TheCAM 180, FIG. 3, polls TCTX 195, FIG. 4, for ARQ Status PDU in FIG. 19.The TCTX 195, FIG. 4, polls the TCRX 200 for ARQ Status bitmap in FIG.7. The TCRX 200, FIG. 4, generates ARQ status and provides it to theTCTX 195 in FIG. 7. The TCTX 195, FIG. 4, sends the ARQ status PDU tothe PDU encoder (PENC0 or PENC1, FIG. 3) in FIGS. 6, 7 and 9. The PDUencoder (PENC0 or PENC1, FIG. 3) encodes the PDU and sends the encodedPDU to the CAM 180. The CAM 180 passes the encoded PDU on to SCC 185 inFIG. 7. The SCC 185, FIG. 3, then provides data to the physical Layer165 in FIG. 21.

Mobile stations 270, FIG. 24, initiate uplink transactions through thetransmission of a BEGIN PDU. The BEGIN PDU is selectively transmittedeither through contention access or reserved access (if the mobilestation 270 has a valid AMI). The parameters indicated by the BEGIN PDUinclude the following: the MSID; the suggested AMI value for thetransaction; the suggested mode (Incremental Redundancy or Fixed Coding)for the transaction; a Mobile Priority Class (MPC); a downlinkincremental redundancy capability; a bandwidth preference (full, doubleor triple rate); and a modulation capability.

If the mobile station 270 does not have a valid AMI, the mobile station270 picks a random value from the set of allowable AMI values andtransmits it within the BEGIN PDU as a suggested AMI. If the mobilestation 270 already has a valid AMI while initiating the transaction, itsuggests the same AMI value. If the suggested AMI and mode areacceptable to the base station 265, it initializes an RLP and providesan acknowledgment (ACK) through the downlink the PCF field. On receiptof the ACK, the mobile station 270 initializes a peer RLP. If thesuggested AMI and/or mode are unacceptable to the base station 265, itprovides an explicit negative acknowledgment (NAK) through the downlinkthe PCF field. Subsequently, it transmits an ARQ Status PDU whichcarries out one of the following functions. AMI, mode and phaseassignment. In this case, the base station 265 assigns an AMI valuerandomly picked from the set of allowable values. It may also assign asuitable mode and phase for the transaction. In the case of a wait forassignment indication, the base station 265 indicates that the mobilestation 270 must wait for an AMI and/or mode assignment. The mobilestation 270 computes a timer which indicates how long it must wait afterreceiving a NAK for a contention access attempt before making anotheraccess attempt. The timer duration is a function of the wait forassignment class (WAC) value assigned by the base station 265, andindicated through the ARQ status PDU. The WAC may be determined by thebase station 265 as a function of the MPC indicated by the mobile 270 inthe BEGIN PDU. On subsequent receipt of an ARQ status PDU while in thisstate, the mobile station 270 initializes an incremental redundancy orfixed coding RLP depending on the mode indicated by the downlink ARQStatus PDU. It is appreciated that the AMI value is assigned within theARQ Status PDU and moves to the assigned phase.

FIG. 25 is a signal flow diagram for an uplink BEGIN PDU handshakebetween a cell 265 and mobile 270. In step 305, on the downlink, themobile 270 sees PCF indication, from the cell 265, that thecorresponding uplink time slot is open for contention. In step 310, themobile 270 sends the cell 265 a MAC layer BEGIN PDU which includes(among other fields) MSID, suggested AMI and suggested mode forsubsequent CONTINUE PDUs. It is appreciated that the suggested AMI mayselectively be different than the last 7 bits of the MSID.

Both steps 305 and 310 are also shown when the SCC 185, FIG. 3, receivesthe contention slot indication via the PCF and indicates a transmissionopportunity to the CAM 180 in FIG. 21. The CAM 180, FIG. 3, polls boththe TCTXs (195, FIG. 4) in FIGS. 19 and 20. The TCTX 195, FIG. 4, on oneof the SAPs (SAP0 or SAP1, FIG. 3) indicates to the CAM 180 that it cansend a BEGIN PDU in FIG. 6. The CAM 180, FIG. 3, polls the TCTX 195,FIG. 4, for the BEGIN PDU in FIG. 19. The TCTX 195, FIG. 4, sends theBEGIN PDU to the PDU encoder (PENC0 or PENC1, FIG. 3) in FIG. 6. The PDUencoder (PENC0 or PENC1, FIG. 3) encodes the PDU and sends the encodedPDU to the CAM 180 which passes it on to the SCC 185 in FIG. 19. The SCC185, FIG. 3, provides the data to the physical Layer 165 in FIG. 21.

In step 315, if the suggested AMI is not being used by any mobilescurrently active on the channel and if the suggested mode is acceptableto the cell 265, the cell 265 assigns the suggested AMI to the mobile270 and acknowledges the BEGIN PDU through the PCF mechanism. The PCFACK indicates that the suggested. AMI and mode are both acceptable tothe cell 265, and the mobile 270 may start transmitting subsequentCONTINUE PDUs. Step 315 was also shown when the SCC 185, FIG. 4,receives an ACK to the transmission of the BEGIN PDU via the PCF andindicates it to the CAM 180 (FIG. 3) in FIG. 21. The CAM 180, FIG. 3,provides a confirmation to the TCTX 195, FIG. 4, that the BEGIN PDU wasreceived in FIG. 19. The TCTX 195, FIG. 4, initializes a radio linkprotocol (RLP) for the mode described earlier in FIGS. 8 and 10.

In step 320, the cell 265 indicates to the mobile 270, through the PCF,that the mobile 270 may selectively proceed with transmission in thenext slot. In step 325, the mobile 270 sends subsequent CONTINUE PDUs inthe initialized mode to the cell 265. It is appreciated to one skilledin the art that steps 320 and 325 may selectively be combined in onetransmission or selectively sent in different time slots.

Both steps 320 and 325 where shown earlier when the SCC 185, FIG. 3,receives a reservation slot indication via the PCF and indicates atransmission opportunity to CAM 180 in FIG. 21. The CAM 180, FIG. 3,polls both the TCTXs (195, FIG. 4) in FIGS. 19 and 20. The TCTX 195,FIG. 4, on one of the active SAP (SAP0 or SAP1, FIG. 3) indicates to theCAM 180 that it can send a CONTINUE PDU in FIG. 9. The CAM 180, FIG. 3,polls the TCTX 195, FIG. 4, for the CONTINUE PDU in FIG. 19. The TCTX195, FIG. 4, sends CONTINUE PDU to the PDU encoder (PENC0 or PENC1, FIG.3) in FIG. 9. The PDU encoder (PENC0 or PENC1, FIG. 3) encodes the PDUand sends the encoded PDU to the CAM 180 which passes it on to the SCC185 in FIG. 19. The SCC 185, FIG. 3, provides the data to the physicalLayer 165 in FIG. 21.

The event that multiple mobiles transmit in the same contention slot andsuggest the same AMI is considered unlikely. However, in the unlikelycase that this event occurs, these mobiles assume the same AMI. It ispossible to resolve the ambiguity by optionally transmitting the MSIDand AMI as a part of the ARQ Status PDUs on the downlink.

FIG. 26 shows a signal flow diagram for an uplink BEGIN PDU handshakebetween the cell 265 and the mobile 270. In step 330, on the downlink,the mobile 270 sees the PCF indication that the corresponding uplinktime slot is open for contention at cell 265. In step 335, the mobile270 sends BEGIN PDU to the cell 265 which includes (among other fields)MSID, suggested AMI and suggested mode.

Both steps 330 and 335 are also show when the SCC 185, FIG. 3, receivesthe contention slot indication via the PCF and indicates a transmissionopportunity to the CAM 180 in FIG. 21. The CAM 180 polls both the TCTXs(195, FIG. 4) in FIGS. 19 and 20. The TCTX 195, FIG. 3, on one of theSAPs (SAP0 or SAP1) indicates to the CAM 180 that it can send a BEGINPDU in FIG. 6. The CAM 180, FIG. 3, polls the TCTX 195, FIG. 4, for theBEGIN PDU in FIG. 19. The TCTX 195, FIG. 4, sends the BEGIN PDU to thePDU encoder (PENC0 or PENC1, FIG. 3) in FIG. 6. The PDU encoder (PENC0or PENC1, FIG. 3) encodes the PDU and sends the encoded PDU to the CAM180 which passes it on to the SCC 185 in FIG. 19. The SCC 185 providesthe data to the physical Layer 165 in FIG. 21.

In step 340, if the suggested AMI is already being used by an activemobile 270 or if the suggested mode is unacceptable, the cell 265 doesnot acknowledge the reception of the PDU to the mobile 270. Step 340corresponds to the SCC 185, FIG. 3, receiving a negative acknowledgmentto the transmission of the BEGIN PDU via the PCF and indicates it to theCAM 180 in FIG. 21. The CAM 180, FIG. 3, indicates to the TCTX 195, FIG.4, that the BEGIN PDU was not received in FIG. 19.

In step 345, the cell 265 sends an ARQ Status PDU to the mobile 270which acknowledges reception of BEGIN PDU and assigns the AMI and/orestablishes the mode to be used for subsequent CONTINUE PDUs. The SCC185, FIG. 3, receives the data from the physical Layer 165 and passes iton to the CAM 180 in FIGS. 21 and 22. The CAM 180, FIG. 3, receives thedata from the SCC 185 and the decoded data is provided to the router(TCRT 210, FIG. 4) in FIG. 19. The TCRT 210, FIG. 4, receives the datafrom the CAM 180, FIG. 3, and passes the ARQ Status PDU to the TCTX 195(FIG. 4) in FIG. 5. The TCTX 195, FIG. 4, receives the ARQ Status PDUfrom the TCRT 210 and initializes AMI and RLP in the uplink. The mode isindicated in FIGS. 8 and 11.

In step 350, the cell 265 indicates to the mobile 270, through the PCF,that mobile 270 may proceed with transmission in the next slot. In step355, the mobile 270 confirms the new AMI in its first CONTINUE PDU. Instep 360, the mobile 270 sends subsequent CONTINUE PDUs to the cell 265.It is appreciate by one skilled in the art that step 350, 355 and 360may selectively be combined in one transmission or sent in differentslots.

In steps 350, 355 and 360, the SCC 185, FIG. 3, receives a reservationslot indication via the PCF and indicates a transmission opportunity toCAM 180 in FIG. 21. The CAM 180, FIG. 3, polls both the TCTXs (195, FIG.4) in FIGS. 19 and 20. The TCTX 195, FIG. 4, on one of the active SAP(SAP0 or SAP1, FIG. 3) indicates to the CAM 180 that it can send aCONTINUE PDU in FIG. 9. The CAM 180, FIG. 3, polls the TCTX 195, FIG. 4,for the CONTINUE PDU in FIG. 19. The TCTX 195, FIG. 4, sends CONTINUEPDU to the PDU encoder (PENC0 or PENC1, FIG. 3) in FIG. 9. The PDUencoder (PENC0 or PENC1, FIG. 3) encodes the PDU and sends to the CAM180 which passes it on to the SCC 185 in FIG. 19. The SCC 185, FIG. 3,provides the data to the physical Layer 165 in FIG. 21.

In the case where an uplink transaction is initiated using a BEGIN PDU,and a simultaneous downlink transaction is initiated before thecompletion of the BEGIN PDU handshake. The uplink BEGIN PDU suggests anAMI and a mode for the transaction. A downlink transaction may beinitiated before the cell acknowledges reception of the BEGIN PDUthrough PCF. In such cases, the BEGIN PDU on the downlink assigns an AMIwhich may or may not be the same as the AMI suggested by the mobile. Inorder to avoid any potential ambiguity, the AMI assigned using thedownlink BEGIN PDU is assumed to take precedence.

FIG. 27 illustrates a signal flow diagram for an AMI assigned on thedownlink different from AMI suggested on the uplink. In step 365, on thedownlink, mobile 270 sees the PCF indication that the correspondinguplink time slot is open for contention with the cell 265. In step 370,the mobile 270 sends BEGIN PDU which includes (among other fields) MSID,suggested AMI and suggested mode. In step 375, the cell 265 sends BEGINPDU which specifies the mode of operation on the downlink and alsoassigns an AMI. This AMI value is different from the AMI suggested bythe mobile station 270. In step 380, the cell 265 does not acknowledgethe reception of the uplink BEGIN PDU. In step 385, the cell 265 sendsan ARQ Status PDU to the mobile 270 which acknowledges reception ofBEGIN PDU and assigns the AMI and/or establishes the mode to be used forsubsequent CONTINUE PDUs. In step 390, the cell 265 indicates to themobile 270, through the PCF, that it may proceed with transmission inthe next slot. In step 395, the mobile 270 confirms a new AMI in itsfirst CONTINUE PDU. In step 400, the mobile 270 sends subsequentCONTINUE PDUs to the cell 265. It is appreciated by one skilled in theart that steps 390, 395 and 400 may selectively combined in onetransmission or sent in different time slots.

FIG. 28 is a flow diagram illustrating an AMI assigned on downlink thatis the same as AMI suggested on the uplink. In step 405, on thedownlink, mobile 270 sees the PCF indication that the correspondinguplink time slot is open for contention. In step 410, the mobile 270sends BEGIN PDU to the cell 265 which includes (among other fields)MSID, suggested AMI and suggested mode for subsequent CONTINUE PDUs. Instep 415, the cell 265 transmits BEGIN PDU which establishes the mode ofoperation on the downlink and assigns an AMI. The assigned AMI happensto be the same as the one suggested by the mobile 270. In step 420, ifthe suggested mode is acceptable to the cell 265, the cell 265acknowledges the BEGIN PDU through the packet channel feedback (PCF)mechanism. The PCF ACK indicates that the suggested AMI and mode areboth acceptable to the cell 265, and the mobile 270 may starttransmitting subsequent CONTINUE PDUs. In step 425, the cell 265indicates to the mobile 270, through PCF, that it may proceed withtransmission in the next slot. In step 430, the mobile 270 sendssubsequent CONTINUE PDUs in the initialized mode. It is appreciated byone skilled in the art that steps 425 and 430 may selectively combinedin one transmission or sent in different time slots.

Stated generally, the present invention is a method of implementing aradio link protocol (RLP) and dynamic partial echo management for atransaction oriented packet data communication system. The methodperforms the steps of determining a data backlog (in the buffers TXB0and TXB1, FIG. 3) with a media access control layer controller (MLC190), and transmitting a BEGIN PDU to a receiver 167. The method furtherincludes the step of initiating a media access control layer transaction(at the MLC 190) in response to the transmitting of the BEGIN PDU. Thedata backlog is indicated to the media access controller by a networklayer 160. The method further includes the steps of stopping datatransmission after transmitting the BEGIN protocol data unit, andwaiting for an acknowledgment message from the receiver 167. Theacknowledgment message from the receiver 167 is controlled by thesub-channel controllers 185.

The present invention is also a system for implementing a radio linkprotocol (RLP) and dynamic partial echo management for a transactionoriented packet data system. The system comprises a media access controllayer controller 190 for determining a data backlog in a media accesscontrol layer buffer (TXB0 and TXB1) and a media access control layertransmitter 166 for transmitting a BEGIN PDU to a receiver 167. Thesystem also includes a means for initiating (such as MCL 190 ormanagement entity 170) a media access control layer transaction inresponse to the transmitting of the BEGIN PDU.

While the specification in this invention is described in relation tocertain implementations or embodiments, many details are set forth forthe purpose of illustration. Thus, the foregoing merely illustrates theprinciples of the invention. For example, this invention may have otherspecific forms without departing from its spirit or essentialcharacteristics. The described arrangements are illustrative and notrestrictive. To those skilled in the art, the invention is susceptibleto additional implementations or embodiments and certain of the detailsdescribed in this application can be varied considerably withoutdeparting from the basic principles of the invention. It will thus beappreciated that those skilled in the art will be able to devise variousarrangements which, although not explicitly described or shown herein,embody the principles of the invention are thus within its spirit andscope.

What is claimed is:
 1. A method of implementing a radio link protocolfor a transaction oriented packet data communication system comprisingthe steps of: determining a data backlog with a media access controllayer controller; transmitting a BEGIN protocol data unit to a receiver;and initiating a media access control layer transaction in response tothe transmitting of the BEGIN protocol data unit; wherein the BEGINprotocol data unit contains a proposed partial echo value.
 2. The methodof claim 1 wherein the step of initiating a media access control layertransaction further includes the step of acknowledging the BEGINprotocol data unit at the media access control layer controllersignifying the acceptance of the proposed partial echo value in themedia access control layer transaction.
 3. The method of claim 1 whereinthe BEGIN protocol data unit contains a proposed mode of operation forthe media access control layer transaction.
 4. The method of claim 3wherein the mode of operation is fixed coding and fixed modulation. 5.The method of claim 3 wherein the mode of operation is fixed coding andadaptive modulation.
 6. The method of claim 3 wherein the mode ofoperation is incremental redundancy coding and fixed modulation.
 7. Themethod of claim 3 wherein the mode of operation is incrementalredundancy coding and adaptive modulation.
 8. The method of claim 3wherein the step of initiating a media access control layer transactionfurther includes the step of acknowledging the BEGIN protocol data unitat the media access control layer controller signifying the acceptanceof the proposed mode of operation for the media access control layertransaction.
 9. The method of claim 1 wherein the data backlog isindicated to the media access controller by a network layer.
 10. Themethod of claim 1 further including the steps of stopping datatransmission after transmitting the BEGIN protocol data unit, andwaiting for an acknowledgment message from the receiver.
 11. The methodof claim 10 wherein both steps are performed at a transmissioncontroller.
 12. The method of claim 1 further including the step oftransmitting at least one CONTINUE protocol data unit after initiatingthe media access control layer transaction with the media access controllayer controller.
 13. The method of claim 1 wherein a transmitter thatis located at a base station sends the BEGIN protocol data unit sendsthe BEGIN protocol data unit comprises.
 14. The method of claim 1wherein a transmitter that is located at a mobile station sends theBEGIN protocol data unit the BEGIN protocol data unit comprises.
 15. Themethod of claim 1, wherein a transmitter sends the BEGIN protocol dataunit, the method further including the step of establishing an assignedlocal identifier used by the transmitter and the receiver for theduration of the transaction.
 16. A method of implementing a radio linkprotocol for a transaction oriented packet data communication systemcomprising the steps of: determining a data backlog with a media accesscontrol layer controller; transmitting a BEGIN protocol data unit to areceiver; initiating a media access control layer transaction inresponse to the transmitting of the BEGIN protocol data unit; andidentifying a mode of operation for subsequent implementations of radiolink protocols and dynamic partial echo management for the transactionoriented packet data system.
 17. The method of claim 16 wherein the modeof operation is fixed coding and fixed modulation.
 18. The method ofclaim 16 wherein the mode of operation is fixed coding and adaptivemodulation.
 19. The method of claim 16 wherein the mode of operation isincremental redundancy coding and fixed modulation.
 20. The method ofclaim 16 wherein the mode of operation is incremental redundancy codingand adaptive modulation.
 21. The method of claim 1, wherein atransmitter sends the BEGIN protocol data unit, wherein the transmitterfurther initializes a radio link protocol upon transmission of the BEGINprotocol data unit.
 22. The method of claim 1 wherein the receiverfurther initializes a radio link protocol upon receiving the BEGINprotocol data unit.
 23. A transaction oriented packet data communicationsystem comprising: a media access control layer transmitter; means fordetermining a data backlog with a media access control layer controller;means for transmitting a BEGIN protocol data unit to a receiver; andmeans for initiating a media access control layer transaction inresponse to the transmitting of the BEGIN protocol data unit; whereinthe BEGIN protocol data unit contains a proposed partial echo value. 24.The system of claim 23 wherein the initiating means further includes ameans for acknowledging the BEGIN protocol data unit at the media accesscontrol layer signifying the acceptance of the proposed partial echovalue in the media access control layer transaction.
 25. The system ofclaim 23 wherein the BEGIN protocol data unit contains a proposed modeof operation for the media access control layer transaction.
 26. Thesystem of claim 25 wherein the mode of operation is fixed coding andfixed modulation.
 27. The system of claim 25 wherein the mode ofoperation is fixed coding and adaptive modulation.
 28. The system ofclaim 25 wherein the mode of operation is incremental redundancy codingand fixed modulation.
 29. The system of claim 25 wherein the mode ofoperation is incremental redundancy coding and adaptive modulation. 30.The system of claim 25 wherein the initiating means further includes ameans for acknowledging the BEGIN protocol data unit at the media accesscontrol layer signifying the acceptance of the proposed mode ofoperation in the media access control layer transaction.
 31. The systemof claim 23 wherein the data backlog is indicated by a network layer.32. The system of claim 23 further including means for stopping datatransmission after transmitting the BEGIN protocol data unit, and meansfor waiting for an acknowledgment message from the receiver.
 33. Thesystem of claim 32 wherein both means comprise a transmissioncontroller.
 34. The system of claim 23 further including means fortransmitting at least one CONTINUE protocol data unit after initiatingthe media access control layer transaction with the media access controllayer controller.
 35. The system of claim 23 wherein the media accesscontrol layer transmitter is located at a base station.
 36. The systemof claim 23 wherein the media access control layer transmitter islocated at a mobile station.
 37. The system of claim 23 furtherincluding means for establishing an assigned local identifier used bythe media access control layer transmitter and the receiver for theduration of the transaction.
 38. A transaction oriented packet datacommunication system comprising: a media access control layertransmitter; means for determining a data backlog with a media accesscontrol layer controller; means for transmitting a BEGIN protocol dataunit to a receiver; means for initiating a media access control layertransaction in response to the transmitting of the BEGIN protocol dataunit; and means for identifying a mode of operation for subsequentimplementations of radio link protocols and dynamic partial echomanagement for the transaction oriented packet data system.
 39. Thesystem of claim 38 wherein the mode of operation is fixed coding andfixed modulation.
 40. The system of claim 38 wherein the mode ofoperation is fixed coding and adaptive modulation.
 41. The system ofclaim 38 wherein the mode of operation is incremental redundancy codingand fixed modulation.
 42. The system of claim 38 wherein the mode ofoperation is incremental redundancy coding and adaptive modulation. 43.The system of claim 23 wherein the media access control layertransmitter further initializes a radio link protocol upon transmissionof the BEGIN protocol data unit.
 44. The system of claim 23 wherein thereceiver further initializes a radio link protocol upon receiving theBEGIN protocol data unit.
 45. A transaction oriented packet datacommunication system comprising: a media access control layer controllerfor determining a data backlog in a media access control layer buffer; amedia access control layer transmitter for transmitting a BEGIN protocoldata unit to a receiver; and means for initiating a media access controllayer transaction in response to the transmitting of the BEGIN protocoldata unit; wherein the BEGIN protocol data unit contains a proposedpartial echo value.
 46. The system of claim 45 wherein the initiatingmeans further includes a means for acknowledging the BEGIN protocol dataunit at the media access control layer signifying the acceptance of theproposed partial echo value in the media access control layertransaction.
 47. The system of claim 45 wherein the BEGIN protocol dataunit contains a proposed mode of operation for the media access controllayer transaction.
 48. The system of claim 47 wherein the mode ofoperation is fixed coding and fixed modulation.
 49. The system of claim47 wherein the mode of operation is fixed coding and adaptivemodulation.
 50. The system of claim 47 wherein the mode of operation isincremental redundancy coding and fixed modulation.
 51. The system ofclaim 47 wherein the mode of operation is incremental redundancy codingand adaptive modulation.
 52. The system of claim 47 wherein theinitiating means further includes a means for acknowledging the BEGINprotocol data unit at the media access control layer controllersignifying the acceptance of the proposed mode of operation in the mediaaccess control layer transaction.
 53. The system of claim 45 wherein thedata backlog is indicated to the media access control layer controllerby a network layer.
 54. The system of claim 45 further including achannel access manager for stopping data transmission after transmittingthe BEGIN protocol data unit, and a media access sub-channel controllerfor waiting for an acknowledgment message from the receiver.
 55. Thesystem of claim 45 wherein the media access control layer transmitter islocated at a base station.
 56. The system of claim 45 wherein the mediaaccess control layer transmitter is located at a mobile station.
 57. Thesystem of claim 45 further including means for establishing an assignedlocal identifier used by the media access control layer transmitter andthe receiver for the duration of the transaction.
 58. A transactionoriented packet data communication system comprising: a media accesscontrol layer controller for determining a data backlog in a mediaaccess control layer buffer; a media access control layer transmitterfor transmitting a BEGIN protocol data unit to a receiver; means forinitiating a media access control layer transaction in response to thetransmitting of the BEGIN protocol data unit; and means for identifyinga mode of operation for subsequent implementations of radio linkprotocols and dynamic partial echo management for the transactionoriented packet data system.
 59. The system of claim 58 wherein the modeof operation is fixed coding and fixed modulation.
 60. The system ofclaim 58 wherein the mode of operation is fixed coding and adaptivemodulation.
 61. The system of claim 58 wherein the mode of operation isincremental redundancy coding and fixed modulation.
 62. The system ofclaim 58 wherein the mode of operation is incremental redundancy codingand adaptive modulation.
 63. The system of claim 45 wherein the mediaaccess control layer transmitter further initializes a radio linkprotocol upon transmission of the BEGIN protocol data unit.
 64. Thesystem of claim 45 wherein the receiver further initializes a radio linkprotocol upon receiving the BEGIN protocol data unit.